Various cardiovascular catheters are well known in the art for performing different diagnostic and interventional medical procedures. In general most cardiovascular catheters include a slender flexible tube that is inserted into an artery of a patient and guided to an access site that allows the medical procedure to be performed.
As an example, an angioplasty catheter is used in a medical procedure in which an inflatable balloon is used to widen a stenotic segment of an artery. As another example, atherocatheters are used to perform another medical procedure known as atherectomy. This procedure cuts away the stenoses and then removes the pieces of plaque which comprised the stenosis from the artery using a vacuum source directed through the catheter.
Medical devices for obtaining a biopsy of different body structures such as the heart, muscles, intestines, and the uterus are also well known in the art. U.S. Pat. No. 3,606,878 to Kellogg, for instance, discloses an early instrument for extracting a biopsy specimen from different regions of the body such as the lungs, chest cavity liner, heart sac or other internal organs.
U.S. Patent No 4,961,430 to Sheahon discloses a cervical biopsy instrument. U.S. Pat. Nos. 4,708,147 to Haaga, U.S. Pat. No. 4,640,296 to Schnepp-Pesch et al, and U.S. Pat. No. 4,620,547 to Boebel disclose particular needle structures for biopsy cannulas.
Other biopsy devices are disclosed in U.S. Pat. Nos. Nos. 4,850,373; 4,903,709; 4,953,559; 4,617,940; 4,099,518; and 4,873,991. Finally a medical instrument known in the art as a Schulz-Caves bioptome is an endomyocardial biopsy device for removing a biopsy sample from the heart.
In general, however, even though biopsy instruments are well known in the art there are no prior art biopsy instruments that are specifically adapted to obtaining a biopsy sample which comprises a segment of arterial wall. An arterial wall is a relatively thin structure. Consequently the possibility of a full-thickness puncture and a resultant hemorrhage exists.
Some of the above cited biopsy catheters, such as the Schulz-Caves bioptome, will remove a segment of tissue in a plane generally perpendicular to a longitudinal axis of the catheter. As is apparent, such an arrangement would be ineffective for use on a thin walled vessel or a long narrow artery. In addition some biopsy catheters are rigid and are not specifically designed for use in arteries.
Moreover, the tissue removed by some prior art biopsy catheters and atherocatheters in general, is not entirely suitable for a subsequent detailed biopsy examination because the tissue has been mutilated and subjected to multiple impacts by the application of a vacuum to the catheter. In addition, the orientation of the tissue in relation to the parent tissue may have been lost. Atherocatheters such as the Simpson Athero-Cath.TM. are designed to remove plaque from the artery and to avoid the arterial tissue.
Information gained from the study of such arterial tissue may be useful in determining the cause and treatment of various cardiovascular maladies. As an example, millions of people suffer from what is called essential hypertension. This hypertension is deemed essential because there is no known cause, let alone cure, for it. These people are treated by receiving drugs that reduce their blood volume or relax their vessels. These drugs do not cure their hypertension, nor shed any light on the underlying causes of high blood pressure.
The current technology allows a physician to take a blood pressure reading, do an angiogram (to visualize arterial profile) and take imperfect curative action if he can determine the cause of narrowing (i.e. fat deposits) and take palliative action if he cannot determine the cause.
The present invention is directed to an apparatus and method for advancing the current understanding of cardiovascular maladies such as hypertension. Another example of the usefulness of this catheter would be in the diagnosis and therapy of atherosclerosis. In this disease there is formation of lipid plaques in the arteries. Current therapies include dietary changes, lipid lowering drugs and interventional cardiology procedures such as balloon angioplasty, atherectomy, excimer laser treatment and stent implantation. However, all these treatment modalities are imperfect especially the interventional ones which have a high rate of early restenosis. The apparatus and method of the present application may be useful in obtaining tissue to determine the mechanism of disease and in evaluating the results of therapy including recently developed genetic techniques.
In addition the apparatus and method of the invention allows a more precise diagnosis of the underlying causes of a particular patient's condition. As an example the apparatus and method may also be helpful in studying differences between people suffering from a variety of vascular diseases. When a precise diagnosis is available, more accurate therapies can be prescribed and unnecessary treatments eliminated.
Accordingly it is an object of the present invention to provide an apparatus and method for obtaining a biopsy sample from the inner layers of a blood vessel such as an artery of a living person. It is another object of the present invention to provide an apparatus and method for obtaining a biopsy sample from the inner layers of a vessel such as an artery in which the biopsy sample is retrieved while minimizing the impacts the biopsy sample would be subject to as would occur with the use of atherocatheters and prior art biopsy catheters that utilize vacuum aspiration to retrieve a sample. It is a further object of the present invention to provide an apparatus and method for obtaining a biopsy sample from a vessel wall in which the orientation of the biopsy sample relative to the parent tissue is preserved. It is yet another object of the present invention to provide an apparatus for obtaining a biopsy sample from an artery of a living person that is relatively easy to use by medical personnel and in which the risk of damage to or puncture of the arterial wall is minimized. It is a further object of the present invention to provide an apparatus for obtaining a biopsy sample from an arterial wall that is simple in construction and relatively inexpensive to manufacture.